@jayskoon93: They do it for traffic. If they're one of the first up it helps bump them up in search results. It also has the added benefit of making people come back to the site multiple times. It's actually a surprisingly common practice when an outlet is covering an event that lasts multiple days (or even just multiple hours).

@Thanatos2k: Just because WoW was the first majorly successful MMO doesn't mean it was the first...it definitely learned from and built off of its predecessors.